financial debt-to-capital ratio

1. What is “enterprise value”? What does it omit?
2. Why might you want to use the financial debt-to-capital ratio rather than the broader total-liabilities-to-assets ratio?
3. Is the financial-debt-to-assets ratio a good measure of firm leverage? If yes, please compute it for IBM for 2005, using information from the preceding questions. If no, please explain why.